1. Field of the Disclosure
The technology of the disclosure relates to use of radio-frequency (RF) communications, including communications involving RF identification (RFID) tags or transponders.
2. Technical Background
It is well known to employ radio-frequency (RF) identification (RFID) transponders to identify articles of manufacture. RFID transponders are often referred to as “RFID tags.” RFID tags are comprised of an antenna coupled to an integrated circuit (IC). An identification number or other characteristic is stored in the IC or memory coupled to the IC. The identification number can be provided to another system, such as an RFID reader, to provide identification information for a variety of purposes. For example, if an RFID tag is an active device, the RFID tag includes a transmitter that can transmit the identification. If the RFID tag is a passive or semi-passive device, the RFID tag does not include a transmitter. The passive or semi-passive RFID tag includes a receiver that receives a wireless RF signal from a transmitter over an antenna, also known as an interrogation signal. The passive or semi-passive RFID tag can respond to receipt of the interrogation signal, including providing identification information, via backscatter modulation communications, as an example.
One application of RFID tags is in communication systems to provide information regarding communication components, such as connectors and adapters as examples. In this regard, the communication components are RFID-equipped. An RFID reader can be provided as part of an RFID system to receive stored information about the RFID-equipped communication components. The RFID reader can interrogate RFID tags disposed in communication components in the range of the RFID reader to automatically discover communication components present in the RFID system. The RFID reader may provide the identification information regarding the communication components to a host computer system. The RFID tags disposed in two communication components can also exchange identification information when connected together to provide connection information to the RFID reader when interrogated. Thus, it is possible to determine when two particular communication components are connected or joined together and when the connection is separated. However, in order for the RFID reader to discover the communication components present in the RFID system and determine when two particular communication components are connected or separated, a significant number of unique queries must be performed by the RFID reader and each of these queries may involve many commands and responses between the RFID reader and the set of RFID tags.
Passive RFID tags have emerged for tracking all manner of objects as a high-performance alternative to bar codes. They are conceptually simple and inexpensive (as little as pennies per tag) and can be read in locations not having a direct line of sight to the tag, through other materials and at relatively long distances (typically, up to 10 meters). Passive RFID tags operate indefinitely without a dedicated power source, such as a battery, deriving their energy solely from radio waves emitted from a nearby reader. Therefore, passive RFID tags can be made as small, thin, and light as a paper label. Passive RFID tags communicate with adjacent RFID readers by selectively reflecting some of the transmitted energy back to the RFID reader, much the same way as a radar works.
RFID tags offer a unique capability in taking inventory of, and inferring the connectivity of, cable components in data centers. Optical cables are made of dielectric materials and have no means for electrically reading serial numbers and configuration data. All markings must appear in printed symbology, and records of interconnections must be kept by manual means. However, the complexity and reconfigurability of interconnects in patch panels call for automated solutions to configuration discovery and asset management, in the interest of accuracy and productivity.
One previously unsolved problem with RFID tags in the intended application is providing a means for RFID tags to exchange information between connected sets, thereby enabling connectivity to be inferred. With their limited power budget, this presents special challenges. In particular, it is difficult to detect when RFID tags are connected, especially when two RFID tags are connected and one of the two RFID tags is unpowered. In addition, it may be desirable that RFID tags sense connection and disconnection events in near-real-time, as the event itself is significant in the operation of a data center. Operations management needs to know when cabling has been reconfigured, with time stamps for keeping an audit trail and with alarms for erroneous events should they occur.
Thus, a need exists for a low-power, instantaneous way of sensing connection and disconnection events between electronic circuits, such as in RFID tags.